Chain winder for a window or door

Abstract

The present invention relates to a chain winder which has a casing, a chain housed at least partially within the casing and extension means operable to cause the chain to extend out from the casing and also to retract back into the casing. The chain winder also includes a clutch mechanism which is operable to allow the chain to be extended out from the casing, or retracted back into the casing, without operating the extension means.

The invention claimed is: 
     
       1. A chain winder comprising:
 a casing having an aperture; 
 a chain having at least one end housed within the casing when the chain extends out of the casing; 
 electrically operated extension means housed within the casing and operable to cause the chain to extend out from the casing and also to retract back into the casing; and 
 a clutch mechanism that is housed within the casing and engageable with the chain, the clutch mechanism being moveable between a first position and a second position and manually accessible from outside the casing through the aperture of the casing to move from the first position to the second position, wherein the clutch mechanism is engaged with the electrically operated extension means when in the first position and disengaged from the electrically operated extension means when in the second position, and 
 wherein the clutch mechanism allows the chain to be extended out from the casing or retracted back into the casing without electrically operating the extension means, when the clutch mechanism is in the second position. 
 
     
     
       2. The chain winder as claimed in  claim 1 , wherein the extension means comprises an electric motor. 
     
     
       3. The chain winder as claimed in  claim 1 , wherein the clutch mechanism comprises:
 a drive gear; 
 a rotatable driven gear which is operatively associated with the chain of the electric chain winder such that rotation of the driven gear in a first direction causes extension of the chain relative to the casing and rotation of the driven gear in a second direction causes retraction of the chain relative to the casing; 
 a clutch gear which can move between a first position and a second position; and 
 a biasing member for biasing the clutch gear into the first position; 
 wherein, in the first position the clutch gear is operatively engaged with the drive gear and the driven gear such that rotation of either of the drive gear or the driven gear causes rotation of the other of the respective drive or driven gear, and in the second position the clutch gear is operatively disengaged from at least one of the drive gear and the driven gear against the bias of the biasing member such that rotation of either of the drive gear or the driven gear does not cause rotation of the other of the respective drive or driven gear. 
 
     
     
       4. The chain winder as claimed in  claim 3 , wherein, in use, the drive gear is rotatably mounted relative to the casing and is operatively associated with the extension means such that operation of the extension means causes rotation of the drive gear. 
     
     
       5. The chain winder as claimed in  claim 4 , wherein the clutch gear moves linearly between the first position and the second position. 
     
     
       6. The chain winder as claimed in  claim 5 , wherein the drive gear has a clutch gear receiving aperture which receives a first portion of the clutch gear, the first portion of the clutch gear being linearly movable within the clutch gear receiving aperture relative to the drive gear when the clutch gear moves between the first and second positions, the clutch pear receiving aperture further including one or more engagement portions which engage with one or more corresponding engagement portions on the first portion of the clutch gear when the clutch gear is in the first position such that neither the drive gear nor clutch gear can rotate without causing rotation of the other, but the drive gear engagement portions disengage from the engagement portions on the first portion of the clutch gear when the clutch gear is in the second position such that the drive gear or clutch gear can rotate without causing rotation of the other. 
     
     
       7. The chain winder as claimed in  claim 6 , wherein the driven gear has an opening which receives a second portion of the clutch gear, the second portion of the clutch gear being linearly movable within the opening relative to the driven gear when the clutch gear moves between the first and second positions, the opening further including one or more engagement portions which engage with one or more corresponding engagement portions on the second portion of the clutch gear when the clutch gear is in the first position and also when the clutch gear is in the second position. 
     
     
       8. The chain winder as claimed in  claim 7 , wherein the engagement portions on the drive gear and the corresponding engagement portions on the first portion of the clutch gear comprise mutually engageable teeth, crenellations or splines, and whilst not necessarily the same, the engagement portions on the driven gear and the corresponding engagement portions on the second portion of the clutch gear comprise mutually engageable teeth, crenellations or splines. 
     
     
       9. The chain winder as claimed in  claim 1 , which can be operated to extend and retract the chain, wherein the chain includes openings at a plurality of locations along the chain, each said opening being operable to receive a removable chain limiter plug, wherein the chain limiter plug can be inserted into an opening at a desired location along the chain so as to define a desired amount of chain extension, and during operation of the electric chain winder to extend the chain, when the chain limiter plug reaches a predetermined position relative to the electric chain winder an extension stop mechanism is operated preventing further extension of the chain. 
     
     
       10. The chain winder as claimed in  claim 9 , wherein the electric chain winder has an electric motor for extending and retracting the chain, and the extension stop mechanism includes a microswitch which is functionally linked to the electric motor and positioned such that when the chain limiter plug moves into contact with the microswitch further extension of the chain is prevented. 
     
     
       11. The chain winder as claimed in  claim 1 , further comprising a chain guide, for guiding movement of the chain inside the electric chain winder, the chain guide defining a chain guide path along which the chain moves during extension and retraction of the chain, the chain guide path having at least two substantially parallel linear sections linked by a curved section, an outer side of the chain guide path being defined by an outer wall and an inner side of the chain guide path being defined by an inner wall, the chain guide further including a rib that abuts the chain as the chain moves through the curved section thereby guiding the chain about the radius of the curved section and preventing links of the chain jamming against themselves or against the outer wall. 
     
     
       12. The chain winder as claimed in  claim 11  wherein the chain guide path is provided with two shoulders, one towards the outer side of the chain guide path and the other towards the inner side of the chain guide path, wherein at least one shoulder is at, or descends to, a lower level in at least one of the curved sections compared to the height of the said shoulder in parallel linear sections of the chain guide path. 
     
     
       13. The chain winder as claimed in  claim 11 , wherein the chain guide path has three substantially parallel linear sections and two curved sections, one of the curved sections linking the first and second of the parallel linear sections, and the other curved section linking the second and third of the parallel linear sections. 
     
     
       14. A clutch mechanism for use located within a casing of a chain winder as claimed in  claim 1 , the clutch mechanism comprising:
 a drive gear; 
 a rotatable driven gear which, in use, is operatively associated with the chain of the chain winder such that rotation of the driven gear in a first direction causes extension of the chain relative to the casing and rotation of the driven gear in a second direction causes retraction of the chain relative to the casing; 
 a clutch gear which can move between a first position and a second position from outside the casing of the chain winder; and 
 a biasing member for biasing the clutch gear into the first position; 
 wherein, in the first position the clutch gear is operatively engaged with the drive gear and the driven gear such that rotation of either of the drive gear or the driven gear causes rotation of the other of the respective drive or driven gear, and in the second position the clutch gear is operatively disengaged from at least one of the drive gear and the driven gear against the bias of the biasing member such that rotation of either of the drive gear or the driven gear does not cause rotation of the other of the respective drive or driven gear. 
 
     
     
       15. The clutch mechanism as claim in  claim 14 , wherein, in use, the drive gear is rotatably mounted relative to the casing and is operatively associated with the extension means such that operation of the extension means causes rotation of the drive gear. 
     
     
       16. The clutch mechanism as claim in  claim 15 , wherein the clutch gear moves linearly between the first position and the second position. 
     
     
       17. The clutch mechanism as claimed in  claim 16 , wherein the drive gear has a clutch gear receiving aperture which receives a first portion of the clutch gear, the first portion of the clutch gear being linearly movable within the clutch gear receiving aperture relative to the drive gear when the clutch gear moves between the first and second positions, the clutch gear receiving aperture further including one or more engagement portions which engage with one or more corresponding engagement portions on the first portion of the clutch gear when the clutch gear is in the first position such that neither the drive gear nor clutch gear can rotate without causing rotation of the other, but the drive gear engagement portions disengage from the engagement portions on the first portion of the clutch gear when the clutch gear is in the second position such that the drive gear or clutch gear can rotate without causing rotation of the other. 
     
     
       18. The clutch mechanism as claimed in  claim 17 , wherein the driven gear has an opening which receives a second portion of the clutch gear, the second portion of the clutch gear being linearly movable within the opening relative to the driven gear when the clutch gear moves between the first and second positions, the opening further including one or more engagement portions which engage with one or more corresponding engagement portions on the second portion of the clutch gear when the clutch gear is in the first position and also when the clutch gear is in the second position. 
     
     
       19. The clutch mechanism as claimed in  claim 18 , wherein the engagement portions on the drive gear and the corresponding engagement portions on the first portion of the clutch gear comprise mutually engageable teeth, crenellations or splines, and whilst not necessarily the same, the engagement portions on the driven gear and the corresponding engagement portions on the second portion of the clutch gear comprise mutually engageable teeth, crenellations or splines.